Halogen-free flame-retardant BT resin-based copper-clad plate and preparation method thereof

Abstract

The present application relates to the technical field of copper-clad plate preparation, and particularly relates to a halogen-free flame-retardant BT resin-based copper-clad plate and a preparation method thereof. The present application adds 3,4-dihydroxybenzaldehyde, triethylamine, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and ethyl acetate to prepare an antibacterial monomer. Then, the Zn-MOF material, the antibacterial monomer and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are used to prepare a flame retardant. Finally, the cyanate ester resin, the bismaleimide resin, the epoxy resin, the flame retardant, the solvent, the filler and the curing agent are added to prepare a resin glue solution. The glass fiber cloth is immersed in the resin glue solution, and then high-temperature curing, copper foil lamination and laminated molding are performed to prepare a finished product. The finished product prepared by the present application has good flame retardance and antibacterial property, and therefore has a wide application prospect in the technical field of copper-clad plate preparation.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate preparation technology, specifically a halogen-free flame-retardant BT resin-based copper clad laminate and its preparation method. Background Technology

[0002] Copper clad laminate (CCL) is a type of board material covered with copper foil and is an important material in the modern electronics industry. As an important material in the modern electronics industry, CCL has irreplaceable and extensive value in emerging technologies and a wide range of applications. With social progress and technological development, its application areas will continue to expand, injecting more advanced, convenient, and intelligent modern elements into people's daily lives and various industries. The modern value of CCL is reflected in the following aspects: (1) Support for high-speed communication technology: With the popularization and development of 5G and higher-speed communication technologies, the application areas of CCL will be further expanded. High-speed communication requires faster signal transmission speeds, so using thinner and smaller CCLs on circuit boards can support higher transmission speeds. (2) A rich industrial chain fosters a diversified economy: As an important material for semiconductor manufacturing, CCL forms a complete chain covering the entire process of raw materials, manufacturing, and processing in its upstream and downstream industrial links, promoting the development of the entire industry and a diversified economic status.

[0003] BT resin-based copper clad laminates possess excellent high-temperature performance, maintaining good mechanical properties under high-temperature environments. They exhibit high flexural strength and surface flatness, making them suitable for applications operating under vibration and high-temperature conditions, such as aerospace and automotive electronics. Furthermore, BT resin-based copper clad laminates have good dielectric constant and dielectric loss, as well as good flame retardant properties, meeting the requirements of high-frequency and high-speed circuit boards, making them suitable for applications in communications, radio frequency, and microwave fields. However, despite these advantages, BT resin-based copper clad laminates are prone to combustion under high-temperature environments, releasing toxic fumes and gases, posing a serious threat to personal safety and equipment. To address this issue, suitable flame retardants can be added to improve the flame retardant properties of BT resin-based copper clad laminates, thereby reducing the risk of fire and protecting personal and equipment safety.

[0004] To overcome the shortcomings of the prior art, the present invention provides a halogen-free flame-retardant BT resin-based copper clad laminate and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a halogen-free flame-retardant BT resin-based copper clad laminate and its preparation method, so as to solve the problems in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a halogen-free flame-retardant BT resin-based copper clad laminate includes the following steps:

[0008] Step 1: Mix 3,4-dihydroxybenzaldehyde, triethylamine and 1 / 3 part by mass of ethyl acetate, stir until dissolved, and add dropwise a mixture of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thionone and 2 / 3 part by mass of ethyl acetate under nitrogen atmosphere. After the addition is complete, heat to 70-80℃ and react for 20-25 h to prepare the antibacterial monomer.

[0009] Step 2: Dissolve the Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve the antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 55-65℃ for 6-7 hours, then add solution 3 and continue the reaction at 85-95℃ for 10-15 hours. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying.

[0010] Step 3: Mix cyanate ester resin, bismaleimide resin and epoxy resin, stir and react at 120-150℃ for 40-60 minutes, then add flame retardant, solvent, filler and curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at high temperature to obtain prepreg; stack copper foil on both sides of the prepreg, and after lamination, prepare the finished product.

[0011] In a more optimized manner, in step one, the content of each component of the antibacterial monomer is as follows: by mass parts, 7-10 parts of 3,4-dihydroxybenzaldehyde, 10-15 parts of triethylamine, 29-35 parts of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione, and 150-200 parts of ethyl acetate.

[0012] In a more optimized manner, in step two, the mass ratio of Zn-MOF material, antibacterial monomer, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(3-6):6.

[0013] In a more optimized manner, in step two, vacuum drying is performed at 80-90℃ for 25-30 hours.

[0014] A more optimized method for preparing Zn-MOF materials is as follows: zinc nitrate hexahydrate and 2-aminoterephthalic acid are dissolved in N,N-dimethylamide, and then triethylamine is added dropwise. After the addition is complete, the mixture is reacted at 100-110℃ for 25-30 hours. After the reaction is complete, the mixture is filtered, washed, and vacuum dried to obtain Zn-MOF materials.

[0015] The optimal reaction mass ratio of zinc nitrate hexahydrate to 2-aminoterephthalic acid is 5:(1.4-1.6).

[0016] Ideally, vacuum dry at 50-60℃ for 10-12 hours.

[0017] In a more optimized manner, in step three, the content of each component of the resin adhesive is as follows (by mass fraction): 30-40% cyanate ester resin, 15-20% bismaleimide resin, 10-14% epoxy resin, 10-15% flame retardant, 10-15% solvent, 5-10% curing agent, and the balance being filler; the solvent is methyl ethyl ketone (MEK), the curing agent is dicyandiamide curing agent, and the filler is silica powder.

[0018] In a more optimized manner, in step three, the product is cured at a high temperature of 140-180℃ for 5-10 minutes.

[0019] In a more optimized manner, the lamination process parameters in step three are: temperature 200-250℃, pressure 2-4MPa, and time 4-6h.

[0020] The beneficial effects of this invention are:

[0021] This invention prepares an antibacterial monomer by adding 3,4-dihydroxybenzaldehyde, triethylamine, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione, and ethyl acetate. A flame retardant is then prepared using Zn-MOF material, the antibacterial monomer, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Finally, a resin solution is prepared by adding cyanate ester resin, bismaleimide resin, epoxy resin, flame retardant, solvent, filler, and curing agent. Fiberglass cloth is impregnated in the resin solution, cured at high temperature, laminated with copper foil, and then pressed to obtain the finished product.

[0022] The invention is characterized in that, in step one, an antibacterial monomer is prepared by adding 3,4-dihydroxybenzaldehyde, triethylamine, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione, and ethyl acetate. The reaction principle of this step is as follows: the hydroxyl group of 3,4-dihydroxybenzaldehyde and the chlorine group of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione undergo a substitution reaction to prepare the antibacterial monomer. On the one hand, the antibacterial monomer introduces aldehyde groups through a reaction, which can further participate in the reaction in step two to prepare flame retardants. Steps one and two are interconnected, making the entire preparation process more efficient and controllable, which helps to improve production efficiency and reduce losses and waste during the preparation process, thus saving resource costs. On the other hand, the antibacterial monomer contains the antibacterial element sulfur and the flame retardant element nitrogen. Sulfur can combine with hydrogen ions in microorganisms and destroy their cell membranes, thereby playing a certain antibacterial role. Nitrogen can enhance the flame retardant properties of the material and effectively delay the occurrence and spread of fire.

[0023] In step two, a flame retardant is prepared using Zn-MOF material, an antibacterial monomer, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The Zn-MOF material contains a certain amount of amino groups on its surface, which can undergo a condensation reaction with the aldehyde groups on the surface of the antibacterial monomer prepared in step one to obtain a Schiff base intermediate. Then, by adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, the electron-deficient C=N bond in the Schiff base intermediate reacts with the PH bond in the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to prepare the flame retardant. The advantages of the flame retardant prepared by this invention are: on the one hand, halogenated flame retardants release toxic fumes and substances during combustion, posing a threat to human health and the environment; in contrast, the nitrogen- and phosphorus-rich flame retardant prepared by this invention typically has lower toxicity and less impact on health and the environment. On the other hand, the flame retardant performance of this flame retardant can be significantly improved by incorporating Zn-MOF material with the flame-retardant elements nitrogen and phosphorus. Zn-MOF material can form a dense char layer during polymer thermal degradation, providing physical protection, preventing the outward diffusion of thermal decomposition products, and reducing the heat release rate. Furthermore, the decomposition products of Zn-MOF material can dilute thermal decomposition products and free radicals, forming more inert gases and inhibiting the combustion process, thereby further improving the flame retardant performance of the material. On this basis, the addition of flame-retardant elements nitrogen and phosphorus can further enhance the flame retardant performance. Nitrogen and phosphorus can form flame-retardant compounds during combustion, effectively improving the flame retardant ability of the material by blocking the combustion source and reducing the combustion rate. Therefore, the combination of Zn-MOF material with the flame-retardant elements nitrogen and phosphorus can bring superior performance in fire resistance and has been widely used in the field of copper clad laminate manufacturing. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Raw material source:

[0026] The following materials were supplied by the chemical composition of the product: cyanate ester resin (TA1000S, Hubei Xingdongcheng Chemical Co., Ltd.); bismaleimide resin (LH, Wuhan Huaxiang Kejie Biotechnology Co., Ltd.); epoxy resin (6101, Dacheng County Lingyue Anticorrosion Materials Co., Ltd.); silica powder (350 mesh, Hebei Leijiang New Material Technology Co., Ltd.); dicyandiamide curing agent (MDH, Hubei Maidehao Chemical Co., Ltd.); fiberglass cloth (500×1400mm, Hejian Yuanchuang Insulation Materials Co., Ltd.); and copper foil (T2 / C1100, Shanghai Xingnuo Industrial Co., Ltd.). One part by weight is 1g.

[0027] Example 1: Step 1: Mix 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate, stir until dissolved, and add dropwise a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate under nitrogen atmosphere. After the addition is completed, heat to 80℃ and react for 25h to prepare the antibacterial monomer.

[0028] Step 2: Dissolve 5g of zinc nitrate hexahydrate and 1.5g of 2-aminoterephthalic acid in 200mL of N,N-dimethylamide, then add 1mL of triethylamine dropwise. After the addition is complete, react at 110℃ for 30h. After the reaction is complete, filter, wash, and vacuum dry at 60℃ for 12h to obtain Zn-MOF material.

[0029] Step 3: Dissolve 1g of Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve 5g of antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 65℃ for 7h, then add solution 3 and continue reacting at 95℃ for 15h. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying at 90℃ for 30h.

[0030] Step 4: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir and react at 150℃ for 60 min, then add 10% flame retardant, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 180℃ for 10 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 250℃ and 4MPa for 6 h to obtain the finished product.

[0031] Example 2: Step 1: Mix 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate, stir until dissolved, and add dropwise a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate under nitrogen atmosphere. After the addition is completed, heat to 77℃ and react for 24h to prepare the antibacterial monomer.

[0032] Step 2: Dissolve 5g of zinc nitrate hexahydrate and 1.5g of 2-aminoterephthalic acid in 200mL of N,N-dimethylamide, then add 1mL of triethylamine dropwise. After the addition is complete, react at 107℃ for 28h. After the reaction is complete, filter, wash, and vacuum dry at 57℃ for 11.5h to obtain Zn-MOF material.

[0033] Step 3: Dissolve 1g of Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve 5g of antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 63℃ for 6.7h, then add solution 3 and continue the reaction at 93℃ for 14h. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying at 87℃ for 29h.

[0034] Step 4: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir at 140℃ for 55 min, then add 10% flame retardant, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 170℃ for 9 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 240℃ and 3.5 MPa for 5.5 h to obtain the finished product.

[0035] Example 3: Step 1: Mix 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate, stir until dissolved, and add dropwise a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate under nitrogen atmosphere. After the addition is completed, heat to 75℃ and react for 23h to prepare the antibacterial monomer.

[0036] Step 2: Dissolve 5g of zinc nitrate hexahydrate and 1.5g of 2-aminoterephthalic acid in 200mL of N,N-dimethylamide, then add 1mL of triethylamine dropwise. After the addition is complete, react at 105℃ for 27h. After the reaction is complete, filter, wash, and vacuum dry at 55℃ for 11h to obtain Zn-MOF material.

[0037] Step 3: Dissolve 1g of Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve 5g of antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 60℃ for 6.5h, then add solution 3 and continue the reaction at 90℃ for 13h. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying at 85℃ for 27h.

[0038] Step 4: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir and react at 135℃ for 50 min, then add 10% flame retardant, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 160℃ for 8 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 225℃ and 3MPa for 5 h to obtain the finished product.

[0039] Example 4: Step 1: Mix 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate, stir until dissolved, and add dropwise a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate under nitrogen atmosphere. After the addition is completed, heat to 73℃ and react for 21h to prepare the antibacterial monomer.

[0040] Step 2: Dissolve 5g of zinc nitrate hexahydrate and 1.5g of 2-aminoterephthalic acid in 200mL of N,N-dimethylamide, then add 1mL of triethylamine dropwise. After the addition is complete, react at 103℃ for 26h. After the reaction is complete, filter, wash, and vacuum dry at 53℃ for 10.5h to obtain Zn-MOF material.

[0041] Step 3: Dissolve 1g of Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve 5g of antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 57℃ for 6.3h, then add solution 3 and continue the reaction at 87℃ for 11h. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying at 83℃ for 26h.

[0042] Step 4: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir at 130℃ for 45 min, then add 10% flame retardant, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 150℃ for 6 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 210℃ and 2.5MPa for 4.5 h to obtain the finished product.

[0043] Example 5: Step 1: Mix 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate, stir until dissolved, and add dropwise a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate under nitrogen atmosphere. After the addition is completed, heat to 70℃ and react for 20h to prepare the antibacterial monomer.

[0044] Step 2: Dissolve 5g of zinc nitrate hexahydrate and 1.5g of 2-aminoterephthalic acid in 200mL of N,N-dimethylamide, then add 1mL of triethylamine dropwise. After the addition is complete, react at 100℃ for 25h. After the reaction is complete, filter, wash, and vacuum dry at 50℃ for 10h to obtain Zn-MOF material.

[0045] Step 3: Dissolve 1g of Zn-MOF material in anhydrous ethanol to obtain solution 1; dissolve 5g of antibacterial monomer in anhydrous ethanol to obtain solution 2; dissolve 6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, slowly add solution 2 dropwise to solution 1, and after the addition is complete, react at 55℃ for 6h, then add solution 3 and continue reacting at 85℃ for 10h. After the reaction is complete, the flame retardant is prepared by rotary evaporation, washing, and vacuum drying at 80℃ for 25h.

[0046] Step 4: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir at 120℃ for 40 min, then add 10% flame retardant, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 140℃ for 5 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 200℃ and 2MPa for 4 h to obtain the finished product.

[0047] Comparative Example 1: Steps 2 and 3 were removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: 7g of 3,4-dihydroxybenzaldehyde, 10g of triethylamine and 50g of ethyl acetate were mixed and stirred until dissolved. Under nitrogen atmosphere, a mixture of 29g of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione and 100g of ethyl acetate was added dropwise. After the addition was completed, the temperature was raised to 80℃ and reacted for 25h to prepare the antibacterial monomer.

[0048] Step 2: By mass fraction, mix 35% cyanate resin, 15% bismaleimide resin and 10% epoxy resin, stir at 150℃ for 60 min, then add 10% antibacterial monomer, 10% methyl ethyl ketone, 15% silica powder and 5% dicyandiamide curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at 180℃ for 10 min to obtain prepreg; laminate copper foil on both sides of prepreg, and laminate at 250℃ and 4MPa for 6 h to obtain the finished product.

[0049] Comparative Example 2: Steps 1, 2, and 3 were removed, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: 35% cyanate resin, 15% bismaleimide resin, and 10% epoxy resin were mixed by mass fraction and stirred at 150°C for 60 min. Then, 10% flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10% butanone, 15% silica powder, and 5% dicyandiamide curing agent were added and stirred thoroughly to obtain a resin solution. Fiberglass cloth was impregnated in the resin solution and cured at 180°C for 10 min to obtain a prepreg. Copper foil was laminated on both sides of the prepreg and laminated at 250°C and 4 MPa for 6 h to obtain the finished product.

[0050] Testing and experimentation:

[0051] Oxygen Index Test: The semi-cured sheet prepared in the embodiment of the present invention was used as a sample. The sample was cut to a size of 70×7×3mm. The initial oxygen concentration was measured according to GB / T 2406.2-2009 standard. The mixed gas of oxygen and nitrogen was introduced into the environment at 25℃ at a flow rate of 40mm / s. Then the oxygen index was calculated using the formula. The higher the oxygen index, the better the flame retardant performance.

[0052] Antibacterial test: The semi-cured sheet prepared in the embodiments of the present invention was used as the sample. The sample was cut to a size of 10×10×2mm and placed in Escherichia coli bacterial solution. After stirring thoroughly for 15 hours, the bacterial concentration before and after stirring was measured, and the sterilization rate was calculated according to the formula. The results are shown in the table below:

[0053] Oxygen Index / % Sterilization rate / % Example 1 35 96 Example 2 35 95 Example 3 34 94 Example 4 34 93 Example 5 33 92 Comparative Example 1 26 93 Comparative Example 2 22 78

[0054] Conclusion: The dosages in Examples 1-5 remained unchanged, with only some reaction parameters modified. Experimental data showed no significant fluctuations in the performance of the samples. Comparative Example 1: Steps two and three were removed, while the rest remained the same as in Example 1. Experimental data showed that compared to Example 1, the oxygen index decreased to 26%, and the sterilization rate was 93%. The reason for this is that, compared to Example 1, Comparative Example 1 removed the MOF material and most of the nitrogen and phosphorus components, thus reducing the flame retardant properties of the prepared sample.

[0055] Comparative Example 2: Steps 1, 2, and 3 were removed, while the rest remained the same as in Example 1. The experimental data showed that, compared with Example 1, the oxygen index decreased to 22% and the sterilization rate decreased to 78%. The reason for this is that the flame retardant prepared by steps 1, 2, and 3 has good flame retardancy and antibacterial properties because it contains antibacterial components sulfur and flame retardant components nitrogen, phosphorus, and MOF. Therefore, removing steps 1, 2, and 3 reduced both the oxygen index and the antibacterial rate.

[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate, characterized in that: Includes the following steps: Step 1: Mix 1 / 3 of the total mass of ethyl acetate, 3,4-dihydroxybenzaldehyde, and triethylamine, and stir until dissolved. Under nitrogen atmosphere, add dropwise the remaining 2 / 3 of the total mass of ethyl acetate and a mixture of 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione. After the addition is complete, heat to 70-80℃ and react for 20-25 hours to prepare the antibacterial monomer. Step 2: Dissolve zinc nitrate hexahydrate and 2-aminoterephthalic acid in N,N-dimethylamide, then add triethylamine dropwise. After the addition is complete, react at 100-110℃ for 25-30 h. After the reaction is complete, filter, wash, and vacuum dry to obtain Zn-MOF material; vacuum drying at 50-60℃ for 10-12 h is required. Zn-MOF material was dissolved in anhydrous ethanol to obtain solution 1; antibacterial monomer was dissolved in anhydrous ethanol to obtain solution 2; 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was dissolved in anhydrous ethanol to obtain solution 3; under nitrogen atmosphere, solution 2 was slowly added dropwise to solution 1, and after the addition was completed, the reaction was carried out at 55-65℃ for 6-7 hours, then solution 3 was added and the reaction was continued at 85-95℃ for 10-15 hours. After the reaction was completed, the flame retardant was prepared by rotary evaporation, washing, and vacuum drying. Vacuum drying at 80-90℃ for 25-30 hours; Step 3: Mix cyanate ester resin, bismaleimide resin and epoxy resin, stir and react at 120-150℃ for 40-60 minutes, then add flame retardant, solvent, filler and curing agent, and stir thoroughly to obtain resin solution; impregnate fiberglass cloth in resin solution, and cure at high temperature to obtain prepreg; stack copper foil on both sides of the prepreg, and after lamination, prepare the finished product.

2. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: In step one, the contents of each component of the antibacterial monomer are as follows (by mass): 7-10 parts 3,4-dihydroxybenzaldehyde, 10-15 parts triethylamine, 29-35 parts 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-thione, and 150-200 parts ethyl acetate.

3. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: In step two, the mass ratio of Zn-MOF material, antibacterial monomer and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(3-6):

6.

4. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: The mass ratio of zinc nitrate hexahydrate to 2-aminoterephthalic acid is 5:(1.4-1.6).

5. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: In step three, the content of each component of the resin adhesive is as follows (by mass fraction): 30-40% cyanate ester resin, 15-20% bismaleimide resin, 10-14% epoxy resin, 10-15% flame retardant, 10-15% solvent, 5-10% curing agent, and the balance is filler; the solvent is methyl ethyl ketone (MEK), the curing agent is dicyandiamide curing agent, and the filler is silica powder.

6. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: In step three, cure at a high temperature of 140-180℃ for 5-10 minutes.

7. The method for preparing a halogen-free flame-retardant BT resin-based copper-clad laminate according to claim 1, characterized in that: In step three, the lamination molding process parameters are: temperature 200-250℃, pressure 2-4MPa, and time 4-6h.